1. Field of the Invention
The invention relates to an enhanced arrangement for securing two mating components together, such as a backplane and a circuit board of a computer, and in particular, to an enhanced arrangement that allows a circuit board to be secured to a backplane without using any tools.
2. Background Information
Computer systems typically have internal mating components that are disposed within a chassis. For example, it is known to place an assembly, including a backplane and various circuit boards, such as a processor card and a so-called memory riser card, within an open chassis. This forms a so-called central electronics complex (CEC) of a computer system. The chassis is subsequently disposed within a computer housing, for example.
The chassis serves to position the circuit boards in a predefined configuration, and acts as an EMC (electromagnetic compatible) shield. An EMC shield is a shield which allows operation in an electromagnetic environment at an optimal level of efficiency, and which allows static charges to be drained to a frame ground. Moreover, the chassis helps to protect the components contained therein from environmental damage, for example, vibrations, which could cause the components to fail.
The backplane, which is wiring board, is typically provided with one or more card slots for the various circuit boards. The respective circuit boards may be removably coupled to the backplane by inserting a corresponding plug connector on the circuit board into the associated backplane card slot. The circuit boards are then held in place using various known means.
For example, each individual circuit board may have a tailstock disposed on a rear edge thereof. As is known, a tailstock is a plate that provides physical support for the associated electrical device (for example, the circuit board), and which may provide for a limited amount of electromagnetic radiation shielding in some situations. Typically, the tailstock is fastened to the chassis using a threaded fastener, such as a screw or bolt, thus securing the associated circuit board. This helps to prevent vibrations or other environmental forces from causing the respective circuit boards from disengaging with the associated card slots of the backplane, which would otherwise cause the circuit boards to become non-functional.
However, as will be appreciated, conventionally a tool is required to remove and/or install the threaded fastener. For example, if a circuit board is to be removed and disengaged from the backplane, a screwdriver may be required to first remove the screw that holds the tailstock of the respective circuit board to the chassis. While this may not present an insurmountable obstacle during the manufacturing of the computer, today""s computers are often modified by the end users. These end users may not have sufficient skill to utilize a screwdriver, or may not have a screwdriver in their possession. Moreover, even if the end user manages to remove the screw, he may inadvertently drop the removed fastener into an inaccessible portion of the chassis. Such a scenario would prevent the circuit board from be re-secured to the chassis until another screw could be obtained. Further, since the threaded fasteners are conventionally formed of a conductive metal, such as steel, the lost screw could cause an electrical short within the computer system.
Thus, there is a need for an arrangement that will allow a circuit board to be removably secured within a chassis without using threaded fasteners.
Further, there is a need for an arrangement that will allow a circuit board to be removably secured within a chassis without using any tools.
Additionally, there is a need for an arrangement that will prevent the inadvertent loss of the fastener used to secure the circuit board to the backplane.
It is also known to provide a tool-less arrangement that includes a number of moving parts attached to the chassis. As shown in FIG. 11, this known arrangement includes a pivotal flap 110 that is secured to a flap holder 112. The flap 110 can be pivoted to rest upon the tailstock 114. The arrangement further includes a handle 116 that can be rotated into engagement with the flap 110, so as to provide a clamping force, thereby securing the circuit board 118 in place. However, this known arrangement is relatively complex, and has numerous parts. Thus, this known arrangement is relatively expensive to manufacture. Therefore, there is a need for a tool-less arrangement that will secure, for example, a circuit board to a backplane, using a simple and uncomplicated configuration.
Furthermore, with the known arrangements used for securing a circuit board to a backplane, it is difficult to determine if the circuit board is properly secured without first removing or otherwise accessing the chassis. That is, the handle and flap of the conventional tool-less arrangement, as well as the conventional threaded fasteners, are disposed within the chassis, and cannot be viewed until the interior of the chassis is accessed. This is a labor intensive operation, and is unlikely to be performed unless a problem has indicated that a circuit board has already moved out of engagement with the backplane. Thus, there is a need for an arrangement that will allow a user to determine if a circuit board is secured to a backplane, without accessing the inside of the chassis.
Additionally, it is also typical to provide the backplane with extra card slots, i.e., card slots that are not populated by circuit boards when the computer is first sold. This allows the end user to populate the computer with circuit boards after the initial purchase, for example, so as to allow the end user to tailor the configuration of the computer to meet specific needs. However, in conventional computer systems, it may be difficult to determine if there are any empty card slots available, without first gaining access to the interior of the chassis. Thus, there is a need for an arrangement that will allow a user to determine if there are any empty card slots on the backplane, without accessing the inside of the chassis.
It is, therefore, a principle object of this invention to provide an enhanced arrangement for securing two mating components together.
It is another object of the invention to provide an enhanced arrangement for securing two mating components together that solves the above mentioned problems.
These and other objects of the present invention are accomplished by the enhanced arrangement for securing two mating components together disclosed herein.
According to one aspect of the invention, a sliding tab is provided that is insertable into a chassis of a computer system so as to secure a printed circuit board, for example, in a desired position. The sliding tab projects through an opening formed in the chassis, so that a front portion of the sliding tab is disposed inside of the chassis, and a rear portion of the sliding tab is positioned generally outside of the chassis. Although other arrangements of the sliding tab are within the scope of the present invention, this particular configuration advantageously allows the rear portion of the sliding tab to be seen and grasped by a user, and allows the front portion of the sliding tab to engage with a tailstock of the circuit board.
The sliding tab according to an exemplary aspect of the invention has a relatively thin, elongated configuration. The front portion of the sliding tab is tapered toward a front edge thereof, and is configured to slope upwards toward the rear portion of the sliding tab. Moreover, the front portion is slightly thinner than a thickness of a central portion and rear portion of the sliding tab. This configuration advantageously provides the front portion of the sliding tab with some resiliency. Further, a step is formed at a junction between a lower surface of the front portion and a lower surface of the central portion, which advantageously provides for a recessed area that accommodates the tailstock of the circuit board.
In another exemplary aspect of the invention, the rear portion of the sliding tab may be provided with a textured surface to facilitate gripping of the sliding tab. Thus, the user will advantageously be able to pull the sliding tab in a reverse direction without losing his grip.
In a further exemplary aspect of the invention, in order to retain the sliding tab within the opening in the chassis, the central portion of the sliding tab may be provided with an elongated slot. A retaining tab may then be disposed on a lower periphery of the opening, and tailored so as to extend across the opening. The retaining tab projects through the elongated slot, and helps to guide the sliding tab in a forward and reverse direction. Moreover, the retaining tab limits an amount of movement of the sliding tab in a forward, reverse and side-to-side direction in a simple and effective manner.
The sliding tab may have a retaining projecting lip on the front edge of the front portion. The retaining projecting lip advantageously serves to ensure the sliding tab slides over the tailstock, rather than under the tailstock. Moreover, the retaining projecting lip advantageously provides a surface that will abut against the chassis or other retaining member to prevent the sliding tab from being inadvertently removed from the opening, i.e., to ensure that the sliding tab is not pulled all the way through the opening.
In a further aspect of the invention, the interior of the chassis includes a shelf that projects away from the opening, and which is essentially level with a lower peripheral edge of the opening. When the sliding tab is installed in the chassis, the front portion of the sliding tab rests upon the shelf. The shelf thus advantageously provides support for the sliding tab.
In order to secure the sliding tab to the chassis and prevent the accidental loss or removal of the sliding tab, the chassis may include a bracket that is provided over the front portion of the sliding tab, so that the sliding tab is sandwiched between the shelf and the bracket. Moreover, in an exemplary embodiment, the bracket is formed from sheet metal, and at least partially covers the opening. The bracket can thus act as an EMC shield, and limit electromagnetic radiation emissions through the opening.
The bracket may also extend over the front portion of the sliding tab, and essentially parallel to the shelf. The bracket thus advantageously prevents the sliding tab from being lifted or moved in an upward direction, and consequently prevents the sliding tab from being removed from its engagement with the retaining tab.
According to an exemplary aspect of the invention, due to the sloping configuration of the front portion of the sliding tab, as the sliding tab is pushed in, the engagement between the upper surface of the front portion and the bracket will cause the front portion of the sliding tab to be urged, with a progressively increasing force, downward and toward the upper flange portion of the tailstock. When the sliding tab is fully pushed in, the sliding tab will thus exert a maximum downward force against the upper flange portion of the tailstock, thus securing the circuit board to the backplane.
Further, when the sliding tab is fully pushed in, the upper flange portion of the tailstock will be advantageously accommodated in the recessed area of the front portion of the sliding tab, i.e., under the sliding tab. This helps to distribute the force applied by the sliding tab over a large area of the upper flange portion, rather than concentrated in only one location.